1 /* dwarf2dbg.c - DWARF2 debug support
2 Copyright (C) 1999 Hewlett-Packard Co
3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 Logical line numbers can be controlled by the compiler via the
23 following two directives:
26 .loc FILENO LINENO [COLUMN]
28 FILENO is the filenumber. */
33 #include "dwarf2dbg.h"
36 #include <elf/dwarf2.h>
38 #define BYTES_PER_ADDRESS (BFD_ARCH_SIZE / 8)
40 /* Since we can't generate the prolog until the body is complete, we
41 use three different subsegments for .debug_line: one holding the
42 prolog, one for the directory and filename info, and one for the
43 body ("statement program"). */
48 /* First special line opcde - leave room for the standard opcodes.
49 Note: If you want to change this, you'll have to update the
50 "standard_opcode_lengths" table that is emitted below in
52 #define DWARF2_LINE_OPCODE_BASE 10
54 #ifndef DWARF2_LINE_BASE
55 /* Minimum line offset in a special line info. opcode. This value
56 was chosen to give a reasonable range of values. */
57 # define DWARF2_LINE_BASE -5
60 /* Range of line offsets in a special line info. opcode. */
61 #ifndef DWARF2_LINE_RANGE
62 # define DWARF2_LINE_RANGE 14
65 #ifndef DWARF2_LINE_MIN_INSN_LENGTH
66 /* Define the architecture-dependent minimum instruction length (in
67 bytes). This value should be rather too small than too big. */
68 # define DWARF2_LINE_MIN_INSN_LENGTH 4
71 /* Flag that indicates the initial value of the is_stmt_start flag.
72 In the present implementation, we do not mark any lines as
73 the beginning of a source statement, because that information
74 is not made available by the GCC front-end. */
75 #define DWARF2_LINE_DEFAULT_IS_STMT 1
77 /* Flag that indicates the initial value of the is_stmt_start flag.
78 In the present implementation, we do not mark any lines as
79 the beginning of a source statement, because that information
80 is not made available by the GCC front-end. */
81 #define DWARF2_LINE_DEFAULT_IS_STMT 1
83 /* Given a special op, return the line skip amount: */
84 #define SPECIAL_LINE(op) \
85 (((op) - DWARF2_LINE_OPCODE_BASE)%DWARF2_LINE_RANGE + DWARF2_LINE_BASE)
87 /* Given a special op, return the address skip amount (in units of
88 DWARF2_LINE_MIN_INSN_LENGTH. */
89 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
91 /* The maximum address skip amont that can be encoded with a special op: */
92 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
94 #define INITIAL_STATE \
95 /* initialize as per DWARF2.0 standard: */ \
100 DWARF2_LINE_DEFAULT_IS_STMT, /* is_stmt */ \
101 0, /* basic_block */ \
102 1 /* empty_sequence */
106 /* state machine state as per DWARF2 manual: */
110 unsigned int filenum;
116 empty_sequence : 1; /* current code sequence has no DWARF2 directives? */
121 any_dwarf2_directives : 1; /* did we emit any DWARF2 line debug directives? */
123 segT text_seg; /* text segment "addr" is relative to */
125 segT line_seg; /* ".debug_line" segment */
126 int last_filename; /* index of last filename that was used */
127 int num_filenames; /* index of last filename in use */
128 int filename_len; /* length of the filename array */
131 int dir; /* valid after gen_dir_list() only */
132 char *name; /* full path before gen_dir_list(), filename afterwards */
136 struct dwarf2_line_info current; /* current source info: */
138 /* counters for statistical purposes: */
139 unsigned int num_line_entries;
140 unsigned int opcode_hist[256]; /* histogram of opcode frequencies */
149 #define out_byte(byte) FRAG_APPEND_1_CHAR(byte)
150 #define out_opcode(opc) (out_byte ((opc)), ++ls.opcode_hist[(opc) & 0xff])
152 /* Output an unsigned "little-endian base 128" number. */
154 out_uleb128 (bfd_vma value)
156 unsigned char byte, more = 0x80;
164 out_byte (more | byte);
169 /* Output a signed "little-endian base 128" number. */
171 out_sleb128 (bfd_signed_vma value)
173 unsigned char byte, more = 0x80;
179 if (((value == 0) && ((byte & 0x40) == 0))
180 || ((value == -1) && ((byte & 0x40) != 0)))
182 out_byte (more | byte);
187 /* Encode a pair of line and address skips as efficiently as possible.
188 Note that the line skip is signed, whereas the address skip is
191 gen_addr_line (int line_delta, bfd_vma addr_delta)
193 unsigned int tmp, opcode;
195 tmp = line_delta - DWARF2_LINE_BASE;
197 if (tmp >= DWARF2_LINE_RANGE)
199 out_opcode (DW_LNS_advance_line);
200 out_sleb128 (line_delta);
201 tmp = 0 - DWARF2_LINE_BASE;
205 tmp += DWARF2_LINE_OPCODE_BASE;
207 /* try using a special opcode: */
208 opcode = tmp + addr_delta*DWARF2_LINE_RANGE;
215 /* try using DW_LNS_const_add_pc followed by special op: */
216 opcode = tmp + (addr_delta - MAX_SPECIAL_ADDR_DELTA)*DWARF2_LINE_RANGE;
219 out_opcode (DW_LNS_const_add_pc);
224 out_opcode (DW_LNS_advance_pc);
225 out_uleb128 (addr_delta);
228 out_opcode (tmp); /* output line-delta */
230 out_opcode (DW_LNS_copy); /* append new row with current info */
234 reset_state_machine (void)
236 static const struct dwarf2_sm initial_state = { INITIAL_STATE };
238 ls.sm = initial_state;
241 /* Set an absolute address (may results in a relocation entry): */
243 out_set_addr (bfd_vma addr)
245 subsegT saved_subseg;
251 saved_subseg = now_subseg;
253 subseg_set (ls.text_seg, ls.text_subseg);
254 sym = symbol_new (".L0\001", now_seg, addr, frag_now);
256 subseg_set (saved_seg, saved_subseg);
258 out_opcode (DW_LNS_extended_op);
259 out_uleb128 (BYTES_PER_ADDRESS + 1);
261 out_opcode (DW_LNE_set_address);
262 expr.X_op = O_symbol;
263 expr.X_add_symbol = sym;
264 expr.X_add_number = 0;
265 emit_expr (&expr, BYTES_PER_ADDRESS);
268 /* Emit DW_LNS_end_sequence and reset state machine. Does not
269 preserve the current segment/sub-segment! */
271 out_end_sequence (void)
277 subseg_set (ls.text_seg, ls.text_subseg);
278 #ifdef md_current_text_addr
279 addr = md_current_text_addr ();
281 addr = frag_now_fix ();
283 subseg_set (ls.line_seg, DL_BODY);
284 if (addr < ls.sm.addr)
291 delta = addr - ls.sm.addr;
293 gen_addr_line (0, delta / DWARF2_LINE_MIN_INSN_LENGTH);
297 subseg_set (ls.line_seg, DL_BODY);
299 out_opcode (DW_LNS_extended_op);
301 out_byte (DW_LNE_end_sequence);
303 reset_state_machine ();
306 /* Look up a filenumber either by filename or by filenumber. If both
307 a filenumber and a filename are specified, lookup by filename takes
308 precedence. If the filename cannot be found, it is added to the
309 filetable the filenumber for the new entry is returned. */
311 get_filenum (int filenum, char *file)
313 int i, last = filenum - 1;
314 char char0 = file[0];
316 if ((unsigned) last >= ls.num_filenames)
317 last = ls.last_filename;
319 /* do a quick check against the previously used filename: */
320 if (ls.num_filenames > 0 && ls.file[last].name[0] == char0
321 && strcmp (ls.file[last].name + 1, file + 1) == 0)
324 /* no match, fall back to simple linear scan: */
325 for (i = 0; i < ls.num_filenames; ++i)
327 if (ls.file[i].name[0] == char0
328 && strcmp (ls.file[i].name + 1, file + 1) == 0)
330 ls.last_filename = i;
335 /* no match: enter new filename */
336 if (ls.num_filenames >= ls.filename_len)
338 ls.filename_len += 13;
339 ls.file = xrealloc (ls.file, ls.filename_len * sizeof (ls.file[0]));
341 ls.file[ls.num_filenames].dir = 0;
342 ls.file[ls.num_filenames].name = file;
343 return ++ls.num_filenames;
347 dwarf2_gen_line_info (bfd_vma addr, struct dwarf2_line_info *l)
349 unsigned int filenum = l->filenum;
350 unsigned int any_output = 0;
351 subsegT saved_subseg;
356 fprintf (stderr, "line: addr %llx file `%s' line %u col %u flags %lx\n",
357 (long long) addr, l->filename, l->line, l->column, l->flags);
359 if (filenum > 0 && !l->filename)
361 if (filenum >= ls.num_filenames)
363 as_warn ("Encountered bad file number in line number debug info!");
367 else if (l->filename)
368 filenum = get_filenum (filenum, l->filename);
370 return; /* no filename, no filnum => no play */
374 ls.line_seg = subseg_new (".debug_line", 0);
375 bfd_set_section_flags (stdoutput, ls.line_seg, SEC_READONLY);
377 /* We're going to need this symbol. */
378 (void) section_symbol (ls.line_seg);
382 saved_subseg = now_subseg;
383 subseg_set (ls.line_seg, DL_BODY);
385 if (ls.text_seg != saved_seg || ls.text_subseg != saved_subseg)
387 if (!ls.sm.empty_sequence)
389 out_end_sequence (); /* terminate previous sequence */
390 ls.sm.empty_sequence = 1;
393 ls.text_seg = saved_seg;
394 ls.text_subseg = saved_subseg;
399 if (ls.sm.filenum != filenum)
402 out_opcode (DW_LNS_set_file);
403 out_uleb128 (filenum);
404 ls.sm.filenum = filenum;
407 if (ls.sm.column != l->column)
410 out_opcode (DW_LNS_set_column);
411 out_uleb128 (l->column);
412 ls.sm.column = l->column;
415 if (((l->flags & DWARF2_FLAG_BEGIN_STMT) != 0) != ls.sm.is_stmt)
418 out_opcode (DW_LNS_negate_stmt);
421 if (l->flags & DWARF2_FLAG_BEGIN_BLOCK)
424 out_opcode (DW_LNS_set_basic_block);
427 if (ls.sm.line != l->line)
430 if (addr < ls.sm.addr)
432 if (!ls.sm.empty_sequence)
435 ls.sm.empty_sequence = 1;
440 gen_addr_line (l->line - ls.sm.line,
441 (addr - ls.sm.addr) / DWARF2_LINE_MIN_INSN_LENGTH);
442 ls.sm.basic_block = 0;
443 ls.sm.line = l->line;
447 subseg_set (saved_seg, saved_subseg);
449 ls.num_line_entries += any_output;
451 ls.sm.empty_sequence = 0;
457 char *str, *slash, *dir_list, *dp, *cp;
460 dir_list = frag_more (0);
463 for (i = 0; i < ls.num_filenames; ++i)
465 str = ls.file[i].name;
466 slash = strrchr (str, '/');
470 for (j = 0, dp = dir_list; j < num_dirs; ++j)
472 if (strcmp (str, dp) == 0)
481 /* didn't find this directory: append it to the list */
482 size_t size = strlen (str) + 1;
483 cp = frag_more (size);
484 memcpy (cp, str, size);
485 ls.file[i].dir = ++num_dirs;
488 ls.file[i].name = slash + 1;
491 out_byte ('\0'); /* terminate directory list */
501 for (i = 0; i < ls.num_filenames; ++i)
503 size = strlen (ls.file[i].name) + 1;
504 cp = frag_more (size);
505 memcpy (cp, ls.file[i].name, size);
507 out_uleb128 (ls.file[i].dir); /* directory number */
508 out_uleb128 (0); /* last modification timestamp */
509 out_uleb128 (0); /* filesize */
511 out_byte (0); /* terminate filename list */
515 print_stats (unsigned long total_size)
517 static const char *opc_name[] =
519 "extended", "copy", "advance_pc", "advance_line", "set_file",
520 "set_column", "negate_stmt", "set_basic_block", "const_add_pc",
525 fprintf (stderr, "Average size: %g bytes/line\n",
526 total_size / (double) ls.num_line_entries);
528 fprintf (stderr, "\nStandard opcode histogram:\n");
530 for (i = 0; i < sizeof (opc_name)/sizeof (opc_name[0]); ++i)
532 fprintf (stderr, "%s", opc_name[i]);
533 for (j = strlen (opc_name[i]); j < 16; ++j)
534 fprintf (stderr, " ");
535 fprintf (stderr, ": %u\n", ls.opcode_hist[i]);
538 fprintf (stderr, "\nSpecial opcodes:\naddr\t\t\t\tline skip\n");
540 fprintf (stderr, "skip: ");
541 for (j = DWARF2_LINE_BASE; j < DWARF2_LINE_BASE + DWARF2_LINE_RANGE; ++j)
542 fprintf (stderr, "%3d", j);
543 fprintf (stderr, "\n-----");
547 j = SPECIAL_LINE (i);
548 if (j == DWARF2_LINE_BASE)
549 fprintf (stderr, "\n%4u: ",
550 DWARF2_LINE_MIN_INSN_LENGTH*SPECIAL_ADDR (i));
551 fprintf (stderr, " %2u", ls.opcode_hist[i]);
553 fprintf (stderr, "\n");
559 bfd_vma addr, body_size, total_size, prolog_size;
560 subsegT saved_subseg, line_prolog;
565 /* no .debug_line segment, no work to do... */
569 saved_subseg = now_subseg;
571 if (!ls.sm.empty_sequence)
573 total_size = body_size = frag_now_fix ();
575 /* now generate the directory and file lists: */
576 subseg_set (ls.line_seg, DL_FILES);
579 total_size += frag_now_fix ();
581 /* and now the header ("statement program prolog", in DWARF2 lingo...) */
582 subseg_set (ls.line_seg, DL_PROLOG);
584 cp = frag_more (15 + DWARF2_LINE_OPCODE_BASE - 1);
586 total_size += frag_now_fix ();
587 prolog_size = total_size - body_size - 10;
589 # define STUFF(val,size) md_number_to_chars (cp, val, size); cp += size;
590 STUFF (total_size - 4, 4); /* length */
591 STUFF (2, 2); /* version */
592 STUFF (prolog_size, 4); /* prologue_length */
593 STUFF (DWARF2_LINE_MIN_INSN_LENGTH, 1);
594 STUFF (DWARF2_LINE_DEFAULT_IS_STMT, 1);
595 STUFF (DWARF2_LINE_BASE, 1);
596 STUFF (DWARF2_LINE_RANGE, 1);
597 STUFF (DWARF2_LINE_OPCODE_BASE, 1);
599 /* standard_opcode_lengths: */
600 STUFF (0, 1); /* DW_LNS_copy */
601 STUFF (1, 1); /* DW_LNS_advance_pc */
602 STUFF (1, 1); /* DW_LNS_advance_line */
603 STUFF (1, 1); /* DW_LNS_set_file */
604 STUFF (1, 1); /* DW_LNS_set_column */
605 STUFF (0, 1); /* DW_LNS_negate_stmt */
606 STUFF (0, 1); /* DW_LNS_set_basic_block */
607 STUFF (0, 1); /* DW_LNS_const_add_pc */
608 STUFF (1, 1); /* DW_LNS_fixed_advance_pc */
610 subseg_set (saved_seg, saved_subseg);
613 print_stats (total_size);
617 dwarf2_directive_file (int dummy)
621 ls.any_dwarf2_directives = 1;
623 if (debug_type == DEBUG_NONE)
624 /* Automatically turn on DWARF2 debug info unless something else
625 has been selected. */
626 debug_type = DEBUG_DWARF2;
628 ls.current.filenum = get_absolute_expression ();
629 ls.current.filename = demand_copy_C_string (&len);
631 demand_empty_rest_of_line ();
635 dwarf2_directive_loc (int dummy)
637 ls.any_dwarf2_directives = 1;
639 ls.current.filenum = get_absolute_expression ();
641 ls.current.line = get_absolute_expression ();
643 ls.current.column = get_absolute_expression ();
644 demand_empty_rest_of_line ();
646 ls.current.flags = DWARF2_FLAG_BEGIN_STMT;
650 listing_source_line (ls.current.line);
655 dwarf2_where (struct dwarf2_line_info *line)
657 if (ls.any_dwarf2_directives)
663 as_where (&line->filename, &line->line);
666 line->flags = DWARF2_FLAG_BEGIN_STMT;